Respiratory Muscle Training Improves Dyspnea and Exercise Performance in Cancer Survivors

Abstract

It is estimated that up to 70% of survivors experience dyspnea at some point in their recovery. Dyspnea is correlated with functional performance (6 minute walk test, 6MWT) and peak exercise (VO2PEAK), both of which predict survival in lung cancer. Respiratory muscle weakness represents one of the primary mechanisms contributing to exertional dyspnea and reduced exercise performance in cancer survivors. Respiratory muscle training (RMT) protocols have been used to reduce dyspnea in patients with non-malignant lung disease; however, no studies have explored respiratory muscle training to alleviate dyspnea in cancer survivors. PURPOSE: Implement a RMT program to reduce the sensation of dyspnea, as well as to improve exercise capacity, functional performance and QoL in breast and lung cancer survivors. METHODS: Eight participants who have completed all therapies (57.3 ± 6.8 years) performed RMT, 3 sets of 15 repetitions against spring loaded inspiratory and expiratory valves, 3 days/week, for 4 weeks. Pre- and Post-RRMT, subjects performed maximal expiratory (MEP) and inspiratory pressures (MIP), exercise tests (VO2Peak, sub-maximal cycling endurance at 70% of peak and 6MWT) and questionnaires related to dyspnea (Baseline Dyspnea Index) and quality of life (SF-36). RESULTS: Four breast and four lung cancer survivors completed the protocol (mean years ± SD from treatment = 4.1±3.0). At baseline, FVC and FEV1 were 80.3±18.5 and 77.2±18.2% of predicted. MIP and MEP were 51.8±20.0% and 94.8±19.2% of predicted. Post-RMT, MIP and MEP increased 26.5±21.2% and 40.1±32.7%, respectively (p<0.005). Time to peak (8.5±3.5 min vs. 10.1±3.2 min, p=0.015) and submaximal endurance (16.5±7.7 vs. 32.4±8.7 min, p=0.007) exercise and the distance covered in the 6MWT (414±91 m vs. 441±97 m, p=0.03) were all significantly longer. Finally, baseline dyspnea index (p=0.02) and quality of life (p=0.04) improved post-RMT. CONCLUSION: These results suggest that a progressive resistance inspiratory and expiratory respiratory muscle training program helps to improve respiratory muscle strength, the sensation of dyspnea, as well as exercise performance and QoL in cancer survivors.